FIG. 8 

 Trephining the Facial Sinuses 



Cross section of the left side of the head of an aged horse at the 

 second molar, seen from the front. F, frontal sinus ; N. nasal sinus, 

 opposite the communication between the nasal and maxillary sinuses ; 

 IM, lateral portion of inferior maxillary sinus ; IM', median 

 portion of inferior maxillary sinus ; SM, superior maxillary sinus ; 

 NF, superior maxillary division of trifacial nerve in its bony conduit ; 

 SZ, subzygomatic artery ; P, palatine artery ; M2, second molar. 



